"Mystery, Alaska" is both the name of the movie, and the name of the fictional town that the characters live in. Much of the town lives for hockey, in the form of the "Saturday Game," a four-on-four game of pond hockey that happens every week and is watched by nearly everyone. All of which is shaken up when a former resident, now a writer (Hank Azaria) has an article published about the town and their game in Sports Illustrated. This eventually leads to the New York Rangers coming to Mystery to play the Mystery team.
Most of the comedy is about the characters in the small town of Mystery, and the critics seemed particularly disappointed that there wasn't enough hockey (and too many characters). The story is also painfully predictable, I'll give them that. But when I watched it, I expected a "comedy" rather than a "hockey comedy" (a distinction that seems to have hung up the majority of the critics), and I found a lot of humour in the movie. The characters are amazingly well drawn: they're all flawed but mostly charming people. And - a thing I was very happy to see - there's very little of the characters stepping outside their own behaviour to make something funny happen. It's funny because of who they already are and what's going on between them.
So it appears the moral of the story is "don't expect a HOCKEY comedy or a surprising plot, and you'll enjoy it." In my case, you'll enjoy it a great deal.